1. Field of the Invention
The present invention relates to a winding apparatus for winding a wire piece having first and second end portions by at least one turn around at least one of a plurality of closed frame-like cores which are laterally formed on a workpiece with a small gap set therebetween and each of which has first and second end faces, while the wire piece is inserted in the core.
2. Description of the Related Art
A magnetic head used, e.g., in a VTR has two closed plate-like frame cores at its end portion. These cores are arranged within the same plane through a gap. Coated wires each having a diameter of, e.g., 50 .mu.m are wound around the cores at portions adjacent to each other and portions spaced apart from each other.
In such a magnetic head, since the gap between cores is small, e.g., about 0.3 mm, and the diameter of each wire is very small, it is difficult to efficiently wind the wires around the cores at high speed.
Japanese Patent Application No. 60-186683 on Aug. 27, 1985 (Japanese Patent Disclosure (Kokai) No. 62-47104 on Feb. 28, 1987), filed by the assignee of the present application, propose an apparatus and method capable of winding wires at higher speed.
According to this method, a magnetic head is mounted on a workpiece holder which is able to rotate about a vertical axis while plate-like frame cores extend upward from the magnetic head. Thereafter, an elongated wire is supplied from a wire supply mechanism to a first end face side of the core, and a free end of the wire is drawn by a vacuum force from a second end face side by using a tension mechanism. The wire is led until a wire portion inserted in a core hole reaches a predetermined length. This wire is fixed to the workpiece holder at the first end face side, and is cut at a position nearer to the wire supply mechanism side than this fixed position. As a result, the wire piece of a desired length which has a first end portion fixed to the workpiece and a second end portion extending far from a second end face is inserted in the core hole.
When a wire piece is to be wound around the inward portion of a core, i.e., a core portion adjacent to the other core, the second end portion of the wire piece is held by the tension mechanism and is kept taut in a desired state. The workpiece holder is then rotated through 180.degree. in the direction to bring the wire piece into contact with the inward portion of the core. In this rotation, a wire hook member mounted on the workpiece holder is moved upward so as to move a wire portion between the second face side of the core and the second end portion of the wire, and the wire piece is deflected upward. In this state, the workpiece holder is rotated while the wire is wound around the wire hook member. With this operation, contact of the wire piece with the adjacent core can be prevented.
After a wire piece portion between the wire hook member and the second end portion is disposed above the gap between the cores, the wire hook member is lowered while a wire holder is raised. As a result, the wire piece is inserted in the gap. After the wire piece is inserted in the gap between the cores, the second end portion of the wire piece is tensioned by the tension mechanism, thereby completing winding of the wire around the inward portion of the core.
When the wire piece is to be further wound, the second end portion is regripped by a wire holding member, and the second end portion is matched with the core hole by rotating the wire holding member. Thereafter, the holding member is moved toward the workpiece holder. The second end portion is then held by a second tension mechanism and is kept taut in a desired stat. After this operation, the next winding operation can be performed in the same manner as described above.
According to the above-described method, elongated wires can be efficiently wound around inward and outward portions of cores, and hence a magnetic head can be efficiently manufactured.
According to the above-described apparatus or method, however, since the gap between cores is very small, when a wire piece is inserted in the gap, the wire piece may be caught by a core. In this case, the coat of the wire may be peeled. In the worst case, the wire may be disconnected. In these cases, the magnetic core becomes a defective product.